Recoupment is currently legal. However, retirement plans sometimes claim that the IRS requires them to recover the overpayments from retirees. This is not true. Beginning in 2015, the IRS has consistently stated that retirement plans may recover overpaid benefits, but that they are not required to recoup overpayments from retirees. Meanwhile, depending on the specific facts of your situation, there may be other legal arguments for why your retirement plan should not recoup against you.